Question : VoIP and Bandwidth in Office Business Center

Hi-
I work for a company that provides fully-furnished & serviced office space for lease. We have about 85 offices and (I believe) the equivalent of three T-1 Internet connections (sorry I know the terminology is wrong!).

My question is this:
We have a client that wants to bring in his own VoIP system and since we provide all of our tenants' Internet connections, he would be using this system through our connection.  There are only 4 or so people in the company, but we need to know approximately how (emphasis on the word approximate; no need for specifics) this would affect our bandwidth use.  In other words, is there a possibility that it would disrupt the connection speed for our other tenants?  We currently do not have any issues with speed and seem to have more than enough bandwidth, but considering the increasing popularity of VoIP we need to know how this will affect us should more people decide to use this (we don't offer the service as of yet; so I am referring to clients bringing in their existing systems).

I have NO idea about the technicalities of bandwidth, so the simpler the answer the better!!  Thank you in advance :)

Answer : VoIP and Bandwidth in Office Business Center

Three T-1 lines is about 4.5mbps (that's megabits per second).  That used to be a lot, but not any more.  Even most home connections are in exceess of 8mbps download, lots are 20mbs and more.

The good news is that IF you have T1's, it's also a 4.5mbps uploading speed - meaning going from the office out to the internet.  That's important in this case for the quality of the tenants voice to the calling party.  

Most voip calls will use 90kbps, or about .09mbps, so that leaves a lot of theoretical bandwidth for the other users.  Still, without something called QOS (Quality of Service), you can't guarantee that 90kbps per line will be available for the VOIP users.

You'll want to see if your router allows for QOS.  If it does you should be able to reserve the right amount of bandwidth to the voip lines to insure that if a neighboring office that's downloading like crazy isn't going to make the voip user's phone call sound terrible.